It is an important part for modern life to go to work, come off duty, travel, or travel on official business by traffic means. On an average each person spends about two hours in traffic means each day, and the greater part of traveling inside or outside the country is spent in traffic process. Most people may read books, newspapers and magazines, listen to music or watch videotapes in the time of traffic process.
Reading books, newspapers or magazines in traffic means can easily make readers uncomfortable; the people therefore prefer audio listening or video watching. Moreover, the development in audio and video products and the competition in traffic means market promote the tendency of audio listening and video watching in traffic means.
In this situation, some businessmen in this field put forward an elongated audio-visual device with a leading end and a trailing end, as disclosed in U.S. Pat. No. 5,775,762. This prior art provided with a screen at front end and a disc player at the rear end for watching and providing audio-visual data. The user can freely select and display the audio-visual content he likes by controlling the control elements of screen and audio-visual device.
However, because the space in the traffic means like cars is limited and the elongated audio-visual device with front and rear end occupied rather large space, the movement and the vision field of the passengers are largely limited. Moreover, the audio-visual device has become a standard equipment of cars due to the competition in car market today, so this kind of audio-visual device is indeed a waste in resources.
Additionally, some businessmen put forward a display device with only screen for cars, as disclosed in the U.S. Pat. No. 5,946,055. This kind of screen has a frame joined to the car roof and is installed near the center or the rear seats of the car. The screen can turns around a rotational axis connected with the frame of the screen and can be stored in the frame. The display side of the screen faces to lower direction of the frame when the screen is stored and the display side faces to the passengers when the screen is turned round.
The kind of display device can be used for car, which has been provided with an audio-visual device and can avoid the waste in resources. However, if a car has not been provided with an audio-visual device, it cannot be provided with only a display device to enjoy the audio-visual display.
Therefore, a need exists for a modular device, which can be assembled from component elements and can improve the prior device. The present invention provides such a device.